Toadfish boatwhistles also function as territorial keep‐out signals.

Abstract

Boatwhistles produced by the toadfish Halobatrachus didactylus seem to function as mate attraction calls during the breeding season. Recent observations, however, indicate that their emission is not restricted to this period, suggesting that boatwhistles may have other functions. The possible dual function of boatwhistles was tested by eliciting sound production from reproductive males in advertisement and territorial defence contexts. These were simulated by creating aggregations of confined nesting males in an intertidal area and by conducting territorial intrusion experiments in tanks, respectively. Furthermore, we investigated whether parental care (eggs in the nest) affected the behavioral responses of territorial males. Nesting males kept in aggregations emitted boatwhistles spontaneously for several days. The relation between calling rate and number of eggs in the nest is under analysis. During territorial intrusions, resident males prevented the entrance of intruders in their shelters by producing...